Research on Printing Parameters and Salt-Frost-Resistance of 3D Printing Concrete with Ferrochrome-Slag and Aeolian Sand (2024-01)¶

Aeolian sand (AS) and ferrochrome slag (FS), an industrial byproduct, are abundant in Inner Mongolia. Rational use of FS and AS resources can lead to better economic benefits. In this study, FS and AS were used as fine aggregates to prepare 3D printed concrete (3DPFAC). The effect of different printing parameters on the mechanical properties of 3DPFAC was investigated and the optimal printing parameters were determined. The durability of 3DPFAC in salt freeze-thaw cycle (FTC) environments was analyzed by FTC tests. The mass loss rate, relative dynamic elastic modulus, and compressive strength loss rate are used to characterize the performance degradation law of 3DPFAC and the mechanism of performance degradation is revealed by SEM, XRD, and bubble spacing analyzer. We conclude that the optimal printing parameters for 3DPFAC are 20 mm print nozzle diameter, 8 mm print layer height, 50 mm/s print travel speed, and consecutive print interval time. Under different production processes, the degree of damage and deterioration of concrete is 3D-Y (loading along the Y direction) > 3D-X (loading along the X direction) > JZ (pouring specimens). After 400 FTCs, the mass loss rates for JZ, 3D-X and 3D-Y were 3.02 %, 3.12 % and 3.56 %, respectively, the relative dynamic elastic modulus decreased to 71.78 %, 66.18 % and 58.64 %, respectively, with compressive strength loss rates of 21.0 %, 22.4 % and 24.0 %. Finally, the damage evolution equation for 3DPFAC is derived using the Weibull distribution model, and the lifetime prediction is performed based on the Weibull distribution damage model. The results can provide a theoretical basis for the application of FS and AS in the 3DPC domain.